Because it isn't dead culturally.
When you see a medieval castle you think about medieval things, when you see Roman architecture you think of Roman things, and since you see Roman architecture all the time in the news, like every time they show the white house etc, it makes sense your brain thinks about the Romans now and then.
Most "trends" from TikTok are made up, stupid, fake, or highly exaggerated. This one is funny because it's actually kinda true for a LOT of people, and has nothing to do with TikTok.
If you ask men how often they think about different manufacturing processes you will probably get similar numbers, or even higher, for the same reason.
But I guess it is similar to the old meme where a woman worries why the guy is so distant that day and if he doesn't like her any longer, and the guy is just thinking hard about why his motorcycle isn't starting.
But that explains it: it is funny the first time you see it, but these differences aren't funny when you already are aware of them. Everything is a first to people. So I don't find it funny since I have seen similar things many times before and have grown tired of it, while others here finds it funny since it is new to them.
I have an Italian American friend who weirdly into the Roman Empire, kind of in a weeb kind of way but he’s a tatted up (Roman Republic full back piece!) Army veteran who would Kimura my ass if I he sees this.
I have a friend just nerdy as shit and into history. He constantly talks about this podcast or that.
I have an ex-roommate / philosophy major, so it comes up a good bit.
I have a friend into Stoicism. Oddly not a philosophy major.
I have a friend rich in small arms, ammunition, and those rice ration buckets because we’re destined for a failure of the Republic as they had.
I have a friend with the same belief, except he just wants to fiddle so I’m pretty sure I won’t bother raiding his house if either of them are correct.
Like, would it be funny if men asked women how often they think about celebrity relationships and drama? People just think about different things.
Is it typical? I don't know.
No, that would be completely unsurprising to most men. Not funny. It would need to be something obvious to women and surprising to men, and surprising to women that it wasn't obvious to men. Then, yes it would be funny.
Since at least the days of the Roman Empire!
> I thought we stopped doing that.
Hollywood would love you to think so, but no, human nature is unchanging. This trend is huge exactly because it reminds us that men and women are different, and humans have derived humor from that fact since the dawn of time.
In the time since then you may have stopped thinking about sex/gender differences, but most people haven't.
I personally wouldn't find your proposal funny, but it might be more well received if you asked men vs women a question like "How often do you think about Taylor Swift's relationship with John Meyer?". That would probably get more views on your tiktoks. IMO part of the humor is that women are so surprised that men frequently think about the Roman Empire [and republic], but for the men it's a matter of course.
Hundreds of thousands of women realizing that unbeknownst to them ALL the men in their lives secretly think about the Roman Empire all the time is hilarious.
Of course, the more specific this phenomenon is, the funnier it is: all men think about history isn't fun. All men are thinking about the Roman Empire is pretty funny. All men are thinking about Pliny the Elder and none of the women in their lives had any idea much funnier.
This is classic benign violation https://en.wikipedia.org/wiki/Theories_of_humor#Benign_viola... The reason I think its a hit because it scales and its totally silly/fun/harmless, relatable beyond expectations, and a welcome distraction to the usual hellscape that is the internet in 2023.
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So the next question is why is it happening, and I have two theories for this:
1. History is stranger than fiction. There's a lot of history geeks out there and there always have been. See stereotype about dads reading WWII books.
2. The Roman Empire is a gateway drug to history for a lot of people. And why not? It's a fascinating period full of whacky characters, and there's been so many movies/shows/plays/games about it that you probably already know enough to dive in and generally know to expect some togas and a dude shouting "I'm Spartacus."
Edit: Why downvote a genuine question? How else would I learn why people find that funny?